INTERNET search king Google's shares have pushed past $US800 ($A780.85) for the first time despite a tough new challenge from Microsoft and looming European Union action over alleged privacy violations.

Google's shares hit $804.00 in early trade on the Nasdaq exchange on Tuesday, pushing the company's market valuation to $US265 billion ($A258.65 billion), after rising 13 per cent from the beginning of 2013 and 33 per cent over the past 52 weeks.

Around 11 am (03.00 AEDT Wednesday) the shares were at $801.71, up 1.1 per cent.

On January 22 Google reported firm 2012 fourth-quarter gains, with profit up 6.7 per cent from a year earlier at $US2.89 billion. For the full year Google's earnings grew 10 per cent to $US10.74 billion, on revenues topping $US50 billion.

Several analysts strengthened their recommendations for the shares with price targets ranging from $800 to $900, the latter from Cantor Fitzgerald.

But the company faces fresh challenges.In a new push for its Outlook email service, Microsoft has launched a negative ad campaign against Google, asking readers if they have been "Scroogled" by Google's use of personal data from users of its Gmail service.

"Google goes through every Gmail that's sent or received, looking for keywords so they can target Gmail users with paid ads."

Microsoft says its Outlook service will not scan emails to target online ads.

On Monday, France's CNIL data protection agency said that European data privacy regulators intended to take action against Google after it failed to follow their orders to comply with EU privacy laws.

"At the end of a four-month delay accorded to Google to comply with the European data protection directive and to implement effectively (our) recommendations, no answer has been given," said CNIL.

National authorities responsible for enforcing data protection laws in the EU said they plan to set up a working group to "coordinate their coercive actions which should be implemented before the summer."

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